Process for preparing anthraquinone-1-acetic acid and esters thereof

ABSTRACT

Anthraquinone-1-acetic acid and esters thereof are prepared by reacting anthraquinone-1-diazonium salts with 1, 1dichloroethylene in the presence of cuprous salts and H2O or alcohols.

United States Patent Ribaldone et al.

[ June 24, 1975 PROCESS FOR PREPARING ANTHRAQUlNONE-I-ACETIC ACID ANDESTERS THEREOF Inventors: Giuseppe Ribaldone, Gallarate;

Giampietro Borsotti, Novara, both of Italy Assignee: Montecatini EdisonS.p.A., Milan,

Italy Filed: May 9, I973 Appl. No.: 358.725

Foreign Application Priority Data May IO, I972 Italy 24l70/72 US. Cl.260/376 Int. Cl I. C09b 1/00 Field of Search 260/376 PrimaryExaminer-Lorraine A. Weinberger Assistant ExaminerE. Jane Skelly [57]ABSTRACT Anthraquinone-l-acetic acid and esters thereof are prepared byreacting anthraquinone-l-diazonium salts with I, l-dichloroethylene inthe presence of cuprous salts and H 0 or alcohols.

3 Claims, No Drawings PROCESS FOR PREPARING ANTHRAQUINONE-l-ACETIC ACIDAND ESTERS THEREOF THE PRIOR ART ltalian Pat. No. 860,016 describes theproduction of methyl anthraquinone-l-acetate by a Diels-Alder reactionbetween naphtoquinone and 3,5-methylhexadienoate, followed bydehydrogenation of the reaction product.

The acylation of olefinic compounds using acyl diazonium halides(chlorides and bromides) in the presence of cupric salts as catalysts ina medium buffered at pH3 4 and at temperatures below 25C (Meerweinreaction) has been described in the literature (Organic Reactions, 11,189 260). The reaction does not take place when the diazonium salts haveH50 as an anion.

The hydrolysis or alcoholysis of trihalides with H 80, is also known(J.A.C.S. 71, M48 (1940); J.A.C.S. 72, 2464 (1950).

However, no prior report of the hydrolysis or alcoholysis of compoundscontaining the group C "Cl SO H has been found.

THE PRESENT INVENTION An object of this invention was to provide a newand relatively simple method for obtaining anthraquinone l acetic acidand esters thereof, which compounds are useful intermediates for thepreparation of dyestuffs and, in particular vat dyestuffs, as disclosedin Italian Pat. Nos. 869,691 and 901,929.

In accordance with the invention, and as indicated in the Abstract fDisclosure, the anthraquinone 1 acetic acid and esters thereof areprepared from anthraquinonel -diazonium salts and l l dichloroethyleneby reacting the salts and chlorinated olefin in the presence of cuproussalts and H 0 or alcohols. The reaction proceeds as shown below:

+ ROE l H2 OR igo dichloroethylene and H 0 or alcohols kept at atemperature ranging from 25C to 35C (and at room temperature), thereaction sets in immediately with the formation of N Once the N,evolution has stopped, and after heating the reaction mixture to convertthe intermediate (ll) completely to the acid or ester, the latterseparate from the reaction mixture in solid form and can be isolated byfiltering.

The process of this invention has a number of advantages over the priorart. One is that the reaction is independent of the reaction medium sothat it is not necessary to control the pH or add buffering substances.Another is that the reaction is not inhibited by alcohols. This is avery important feature of the present process, inasmuch as it ispossible to obtain the esters directly from the anthraquinone aceticacid by operating in an alcoholic medium. Still another advantage, andone that was not predictable, resides in the possibility of provokingthe reaction between the anthraquinone diazonium salt andl,1-dichloroethylene when the salifying anion is HSOf". This isimportant because the an thraquinone diazonium sulphate is more easilyprepared and can be obtained in much purer form than theanthraquinonazium halides.

The hydrolysis and the alcoholysis of intermediate (ll) takes placedirectly in the diazonium medium without the addition of othersubstances, for instance without the addition of H The followingexamples are given to illustrate the invention and are not intended tobe limiting.

EXAMPLE 1 Into a flask provided with a thermometer, a stirrer, a refluxcoolant connected at its lower part with a valve containing sulphuricacid for controlling the development of gas, there were introduced:

15 g of anthraquinone-diazonium sulphate, at 97% (0.043 moles),

48.4 g (0.50 moles) of l,l-dichloroethylene and cc 99% methanol.

The mixture was heated to 30C and then there were admixed 0.2 grams ofcuprous chloride. Thereupon, nitrogen immediately started to develop.The temperature was maintained at 30 35C by external refrigeration in awater bath, in as much as the reaction is of an CHZ- C Cl exothermiccharacter. After about 30 minutes, the development of nitrogen stoppedand from the mixture there started to form a methyl ester precipitate.Thereupon, the mixture was stirred for 30 minutes, then the refluxcoolant was removed and a distilling head was applied. Distilling wascarried on until the vapors has reached 65C. Thereby were obtained 60 ccof distillate containing 32.5 g of l,1-dichloroethylene, which wasrecycled into a successive operation, reintegrating it with methanol andl,l-dichloroethylene.

The reaction mixture was refluxed for 30 minutes and then cooled down to20C whereupon the precipitate was filtered and washed with methanol,then with a diluted solution of ammonia, and finally with water until itwas neutral.

Thereby were obtained 1 L2 g of methyl anthraquinone-l-acetate which hada titer of 97.9%, correspond ing to a yield of 98%.

A sample of the product when crystallized from butanol or Sublimatedunder vacuum, melts at l90.5 l9l.5C.

EXAMPLE 2 Example 1 was repeated, using the same equipment and the sameoperating conditions, and the following materials:

g (0.043 mole) of 97% diazonium sulphate,

48.4 g (0.50 mole) of l,l-dichloroethylene,

100 cc of ethanol at 99.5% and 0.2 of cuprous chloride.

In this case the distillation was carried on until the vapors attained78C. Thereby were recovered 33 g of l,l-dichloroethylene and 10.8 g ofethyl anthraquinone-l-acetate were obtained with a titer of 83%,corresponding to a yield of 69.5%.

A sample of the product, purified by sublimation under vacuum or bycrystallization from butanol, melted at 203.5 204C.

The elementary analysis, the infra-red spectrum and the NMR agree withthe structure of the compound.

anthraquinonel EXAMPLE 3 Operating with the same equipment described inExample l, the following substances were reacted with each other:

15 grams of anthraquinone-l-diazonium sulphate at 97% (0.043 mole),

48.7 g of l.l-dichloroethylene (0.50 mole),

I00 cc of acetone; and

5 cc of water.

The whole mixture was then heated up to 30C and 0.2 g of cuprouschloride was added to it. During the development of nitrogen thetemperature was kept at between 30 and 32C. The mixture was heated up to35C for 30 minutes, thereafter the mass was distilled until the vapoursattained 56C. Thereby 36.3 g of l, l dichloroethylene were recovered.The mixture was then cooled down to 20C and the precipitate wasfiltered. Thereby 8.0 g of anthraquinone-l-acetic acid were obtained. lthad a titer of corresponding to a yield of 65%.

A sample of the product, crystallized from butanol, melted at 245C.

We claim:

1. Process for the preparation of anthraquinone-lacetic acid and estersthereof, characterized in that an anthraquinone-l-diazonium sulphate isreacted with l,l-dichloroethylene in the presence of cuprous salts and H0 or alkanols containing from I to 5 carbon atoms, at temperaturesbetween 25 and 35C, at atmospheric pressure and after the removal of anyunreacted l,l-dichloroethylene, the anthraquinone-lacetic acid or esterthereof is separated from the reaction medium in solid form.

2. The process according to claim 1, characterized in that theanthraquinone-l-diazonium salt and 1,1- dichloroethylene are reacted inH 0.

3. The process according to claim 1, characterized in that theanthraquinone-l-diazonium salt and l,ldichloroethylene are reacted in analkanol containing from 1 to 5 carbon atoms.

* k k 1' l

1. PROCESS FOR THE PREPARATION OF ANTHRAQUINONE-1-ACETIC ACID AND ESTERSTHEREOF, CHARACTERIZED IN THAT AN ANTHRAQUINON-1-DIAZONIUM SULPHATE ISREACTED WITH 1,1-DICHLOROETHYLLENE IN THE PRESENCE OF CUPROUS SALTS ANDH2O OR ALKANOLS CONTAINING FROM 1 TO 5 CARBON ATOMS, AT TEMPERATURESBETWEEN 25* AND 35*C, AT ATMOSPHERIC PRESSURE AND AFTER THE REMOVAL OFANY UNREACTED, 1,1-DICHLOROETHYLENE, THE ANTHRAQUINONE-1ACETIC ACID ORESTER THEREOF IS SEPARATED FROM THE REACTION MEDIUM IN SOLID FORM. 2.The process according to claim 1, characterized in that theanthraquinone-1-diazonium salt and 1,1-dichloroethylene are reacted inH2O.
 3. The process according to claim 1, characterized in that theanthraquinone-1-diazonium salt and 1,1-dichloroethylene are reacted inan alkanol containing from 1 to 5 carbon atoms.